TWI906558B - Optical device having optical and mechanical properties - Google Patents

Abstract

An optical device includes a substrate and a coating applied to the substrate, wherein the optical device has a first side exposed to an environment and a second side that is unexposed.

Description

Optical devices with optical and mechanical properties

The present invention relates generally to an optical device comprising a substrate and a coating applied to the substrate, wherein the optical device has a first side exposed to the environment and a second side not exposed to the environment.

Optical devices used in optical sensors have become increasingly important with the advent of semi-autonomous, fully autonomous, and remote-controlled vehicles. For example, there is growing interest in the application of LIDAR (Light Detection and Ranging) technology in automobiles. However, the use of optical devices in optical sensors raises concerns about whether the sensors can withstand mechanical, optical, and environmental factors that may damage or adversely affect their function. For instance, sensors are exposed to environmental factors such as rain and wind, which may damage, scratch, or affect their durability and operability.

In one state, a substrate and a coating applied to the substrate are revealed, wherein the optical device has a first side exposed to the environment and a second side not exposed to the environment.

Additional features and advantages of the various specific examples will be partially set forth in the following description, and will be partly apparent from the description or may be learned through practice of the various specific examples. The objectives and other advantages of the various specific examples will be achieved and attained by means of the elements and combinations specifically pointed out in the description herein.

It should be understood that both the foregoing general description and the following detailed description are merely illustrative and explanatory, and are intended to provide explanations of various specific examples of the teachings of this invention. The layers/components shown in each figure may be described with respect to a particular figure, but it should be understood that the description of a particular layer/component will apply to the equivalent layer/component in other figures.

In a wide and varied specific example, as shown in Figure 1, an optical device 10 is disclosed, comprising a substrate 20 and at least one coating 30 applied to the substrate 20, wherein the optical device 10 has a first side exposed to the environment and a second side not exposed to the environment. The "exposed" first side means facing the environment, such as light, air, dust, wind, etc. The "unexposed" second side means not facing the environment and may include applications to other devices, such as windows, sensors (e.g., LiDAR sensors), or lenses, such as freestanding optical lenses or lenses as part of a composite optical system.

The disclosed optical device 10 may include at least one coating 30, as disclosed above, which can protect other devices from mechanical, optical, chemical, and environmental factors. The at least one coating 30 can provide at least one function. The at least one coating 30 may include one or more coatings to provide multiple functions to the optical device 10. Accordingly, the at least one coating 30 may include one or more coatings 30 on the first exposed side and/or the unexposed second side of the substrate 20 to optimize the function of each coating 30 of the optical device 10.

The matrix 20 of the optical device 10 can be any applicable material. Non-limiting examples of the matrix 20 include plastics, synthetic sapphire, glass, synthetic diamonds, optical ceramic materials, optically graded polymers, and light-transmitting matrices having the absorption spectrum required for the functional application of the optical device 10, such as silicon. Optically graded polymers include polycarbonate, acrylate polymers, and cyclic olefin polymers. Various types of glass, including chemically strengthened glass, can be used.

In one embodiment, as shown in FIG. 6, the optical device 100 may include more than one substrate 110a, 110b. Including more than one substrate 110a, 110b can improve the security of the optical device 100 and the sensors it employs. Furthermore, including more than one substrate 110a, 110b in the optical device 100 can improve the structural strength and/or elasticity of the optical device 100. The optical device 100 may include two or more substrates 110a, 110b. The two or more substrates 110a, 110b may be laminates, wherein the two or more substrates 110a, 110b are fixed together. In one embodiment, an adhesive may be included between the two or more substrates 110a, 110b to form a laminate. Laminate substrates can provide thinner and stronger optical devices 100. However, the thickness of a single substrate or laminate substrate is not a limiting factor in selecting a suitable substrate for the optical device 100.

At least one substrate 110a, 110b may be the same or different. In one embodiment, the first substrate 110a may be made from a hard optical material, depending on the application and location, and may be derived from chemically strengthened glass to inherently extremely hard and impact-resistant materials, such as synthetic sapphire or diamond. The first substrate 110a may include a coating 30 that provides mechanical and protective functions on a first exposed side, and may include a second substrate and/or coating 30 that provides optical functions on a second unexposed side. The second substrate 110b may be used as a carrier for an optical coating that provides additional protection for the optical device 10.

The substrates 20, 110a, and 110b used in the optical device 10 can be selected based on factors such as safety, cost, and weight. The selection of substrates 20, 110a, and 110b is a variable in the formation of the optical devices 10 and 100. In particular, the selection of substrates 20, 110a, and 110b can change the layer order of the coatings 30 in the optical devices 10 and 100.

Figure 2-5 illustrates various optical devices 10 discussed herein. It is essentially illustrative only. It should be understood that the order of the coatings on the first exposed side and the second unexposed side can be varied. Furthermore, the types of coatings present on the first exposed side and the second unexposed side can be varied. Generally, a coating 30 providing mechanical and protective functions is present on the first exposed side of the optical device, and a coating 30 providing optical functions is present on the second unexposed side of the optical device. The coating 30 of Figure 2-5 is described in more detail below.

As shown in Figure 2, the illuminating optical device 10 includes an anti-reflective coating 30a with anti-fouling treatment and a substrate 20 on the first exposed side, and a conductive coating 30b and an anti-glare coating 30c on the second unexposed side.

As shown in Figure 3, the illuminating optical device 10 includes an anti-reflective coating 30a with anti-fouling treatment and a substrate 20 on the first exposed side, and a conductive coating 30b, an anti-glare coating 30c and an anti-reflective coating 30e on the second unexposed side.

As shown in Figure 4, the illuminating optical device 10 includes an anti-reflective coating 30a with anti-fouling treatment and a substrate 20 on the first exposed side, and a conductive coating 30b, a bandpass filter 30d and an anti-glare coating 30c on the second unexposed side.

As shown in Figure 5, the illuminating optical device 10 includes an anti-reflective coating 30a with anti-fouling treatment and a substrate 20 on the first exposed side, and a conductive coating 30b, a bandpass filter 30d, an anti-glare coating 30c and an anti-reflective coating 30e on the second unexposed side.

The optical device 10 may include a coating 30, such as an antireflective coating 30e, applied to a substrate 20. In one embodiment, the antireflective coating 30e may be present on a first side of the optical device 10. The antireflective coating 30 may also be treated to impart stain-resistant properties 30a, as shown in Figures 2-5. In another embodiment, the antireflective coating 30e may be present on a second side of the optical device 10, as shown in Figures 3 and 6. The optical device 10 may include an antireflective coating 30a with stain-resistant treatment on the first side and an antireflective coating 30e (without stain-resistant treatment) on the second side.

The antireflective coating 30e can be a dielectric stack and can reduce light reflection at the interface with the substrate 20. Suitable dielectrics for forming the dielectric stack include metal oxides such as _TiO2 , _Ta2O5 , _ZrO2 , and _SiO2 , which are optically isotropic and exhibit high transparency in the visible light wavelength range (e.g., from 400 _nm to 700 nm). The antireflective coating 30e can be a stack comprising a first plurality of dielectric layers having a first refractive index (e.g., a low refractive index), such as _SiO2 or magnesium fluoride ( _MgF2 ), which are interleaved with a second plurality of dielectric layers having a second refractive index (e.g., a high refractive index). Unlimited examples of high refractive index materials include niobium oxide, tantalum oxide, aluminum oxide, titanium oxide, zirconium oxide, and combinations thereof.

The antireflective coating 30e can be formed as a stack of NbTiO_{_x} , SiO_₂, or similar layers. In one state, the antireflective coating 30e can be a thin film dielectric stack as follows: the first layer is approximately 50 nm of NbTiO_{_x}, the second layer is approximately 18 nm of SiO_₂, the third layer is approximately 16 nm of NbTiO_{_x}, and the fourth layer is approximately 101 nm of SiO_₂ .

Optical device 10 may include a coating 30, such as a protective coating, applied to a substrate. In one embodiment, the protective coating may be present on a first side of the optical device. Optical device 10 may include a protective coating alone or in combination with an antireflective coating 30e. In one embodiment, the protective coating is applied to the antireflective coating 30e, which is applied to the substrate 20. Both the protective coating and the antireflective coating 30e are on the first side of the optical device 10.

In one embodiment, the protective coating may comprise a fluorinated alkyl ether polymer having a functionalized silane. An example of this compound has the following general formula: R _m -Si-X _n (1), where R comprises a fluorinated alkyl ether repeating unit, and X may be an alkoxy group, chloride, or amino group, where m+n equals 4. For example, trimethoxysilane-functionalized poly(perfluoropropyl ether) and silazane-functionalized poly(perfluoroethyl ether) are two such compounds.

The protective coating may be durable and may include compounds having the following simplified formula: _CF3- [CH( _CF3 )-CH2- _O- ] _x - _CONCH3- ( _CH2 ) ₃ -Si-( _OC2H5 ) ₃ (2), where x is an integer from 7 _to 11. This compound may also include divalent linked groups (i.e., _-CONCH3- ( _CH2 ) _3- ). Of course, compounds that are structurally and functionally similar to those shown in formula (2) may also be used in the protective coating. In particular, N-methyl-N-(triethoxypropyl)-2-[α-heptanefluoropropoxy]{poly(oxy(trifluoromethyl)-1,2-ethanediyl)}tetrafluoropropoxyamine and commercially available compounds may be used in the protective coating.

Methods of applying a protective coating may include wet techniques such as dipping, flowing, wiping, and/or spraying the surface with a liquid, solution, or gel-like carrier containing the coating compound; and dry techniques such as applying coating compound vapor to the surface (under ambient pressure or in a vacuum).

The optical device 10 may include a coating 30, such as a conductive coating 30b, applied to a substrate 20, as shown in Figures 2-5. The conductive coating 30b may be present on a second side of the optical device 10. The conductive coating 30b may be a low surface energy treatment for use as a surface for scavenging, scavenging water, and scavenging dust. The coating 30b may have a low coefficient of friction, such as less than 0.08. Thus, the conductive coating 30b can reduce the sensitivity of the optical device 10 to damage from abrasive media.

The conductive coating 30b may include indium tin oxide (ITO), nanoparticle-based transparent composites, and other commonly used optically transparent conductors. In one state, the conductive coating 30b may be transparent at the operating wavelength of the LIDAR sensor (e.g., between approximately 850 nm and approximately 2000 nm).

The conductive coating 30b can be used as a heating element to increase the temperature of the optical device 10, such as from about 30 ^° C to 80 ^° C. As a heating element, the optical device 10 including this coating 30b can be used to eliminate and/or reduce at least one of the following: the risk of window fogging with additional sensors, the risk of water vapor condensation, and increase the decontamination of the first exposed side of the optical device 10.

In addition, the conductive coating 30b can increase the hydrophobicity and oleophobicity of the external antireflective coating 30 on the first side of the substrate by increasing the efficiency of water and dirt removal.

The conductive coating 30b may not have sufficient mechanical durability to create a robust surface. Therefore, the conductive coating 30b should be applied to the second side, that is, the side of the optical device facing the sensor.

The optical device 10 may include a coating 30, such as an anti-glare coating 30c, applied to a substrate 20. The anti-glare coating 30c may be present on a second, unexposed side of the optical device 10, as shown in Figures 2-5. Both the anti-glare coating 30c and the conductive coating 30b may be present on the second, unexposed side of the optical device 10. In one embodiment, the anti-glare coating 30c may be applied to the conductive coating 30b, which is applied to the substrate 20.

An example of the anti-glare coating 30c can be a multi-layered structure of a ring polarizer, including a linear polarizer incorporating a quarter-wavelength optical delayer. The delayer is a birefringent material that alters (delays) the polarization state or phase of light passing through it. The delayer has a fast axis (abnormal) and a slow axis (normal). When polarized light passes through the delayer, light traveling along the fast axis passes through the delayer faster than light traveling along the slow axis. In the example of a quarter-wavelength delayer, the waveplate delays the velocity of one of the polarization components (x or y) by a quarter of the phase of the other polarization components. The polarized light passing through the quarter-wavelength delayer thus becomes circularly polarized. The anti-glare coating 30c can reduce and/or eliminate glare at the operating wavelength of the sensor protected by the optical device 10. The anti-glare coating 30c also allows for the analysis of the polarization state of a single beam.

The optical device 10 may include a coating 30, such as a bandpass filter 30d, applied to a substrate 20. The bandpass filter 30d may be present on a non-exposed second side of the optical device 10, as shown in Figures 4-5. The bandpass filter 30d may be applied to an anti-glare coating 30c, which may be applied to a conductive coating 30b applied to the substrate 20. In one embodiment, the bandpass filter 30d, the anti-glare coating 30c, and the conductive coating 30b may all be present on the non-exposed second side of the optical device 10. In one embodiment, an anti-glare coating 30c may be applied to a conductive coating 30b, which is applied to a substrate 20.

A 30d bandpass filter can be implemented using a full stack of low- and high-refractive-index materials. Each layer can be deposited at the desired filter wavelength as a quarter-wave (QW) thickness. Each portion of the reflector (which may consist of a single layer) is called a quarter-wave stack (QWS). The filter bandwidth is a function of the reflectivity of the quarter-wave stack within the structure. The center wavelength of the passband is determined by the thickness of the dielectric material. The dielectric material used for the quarter and/or half-wave layers has a refractive index ranging from 1.3 to over 4.0. For example, some suitable materials include: magnesium fluoride (1.38), thorium fluoride (1.47), cryolite (1.35), silicon dioxide (1.46), aluminum oxide (1.63), iron oxide (1.85), tantalum pentoxide (2.05), niobium oxide (2.19), zinc sulfide (2.27), titanium oxide (2.37), silicon (3.5), germanium (4.0), and lead telluride (5.0). Other dielectric materials can also be used. In addition, a 30d all-dielectric bandpass filter can also be combined with anti-reflective properties.

In one embodiment, the bandpass filter 30d can be a polymeric coating containing a suitable dye mixture to create the desired absorbance or a combination of dielectric and polymeric structures.

The bandpass filter 30d allows light of the wavelength at which it interacts with the sensor to pass through while blocking all other wavelengths. For example, the bandpass filter 30d can block wavelengths in the visible and near-infrared spectral range, such as from approximately 400 to approximately 850 nm, and can transmit wavelengths above 850 nm. In this way, the bandpass filter 30d can reduce and/or block unwanted radiation from reaching the sensor attached to the optical device 10.

The optical device 10 can be attached to other devices to form an optical system. Other devices may be windows, sensors (e.g., LiDAR sensors), or lenses, such as freestanding optical lenses or lenses. The optical device 10 can be attached to other devices using a learned deposition process.

This invention also discloses a method for manufacturing the optical device 10. The optical device 10 can be formed using semiconductor processes.

This invention also discloses a method for manufacturing an optical system. The optical device 10 can be attached to other devices to form an optical system by a learned deposition process.

As will be apparent to those skilled in the art from the foregoing description, the teachings of this invention can be implemented in various forms. Therefore, although these teachings have been described in conjunction with specific examples and embodiments, the actual scope of the teachings of this invention should not be limited thereto. Various changes and modifications can be made without departing from the scope of the teachings herein.

The scope of this disclosure will be explained broadly. This invention intends to disclose equivalents, components, systems, and methods for achieving the devices, activities, and mechanical actions disclosed herein. For each of the disclosed devices, articles, methods, components, mechanical elements, or mechanisms, this invention also intends to cover in its disclosure and teaching equivalents, components, systems, and methods for practicing the various forms, mechanisms, and devices disclosed herein. Furthermore, this invention relates to coatings and their various forms, features, and elements. Such devices may be dynamic in their use and operation, and this invention intends to cover equivalents, components, systems, and methods of the use of such devices and/or articles, as well as their various forms, which are consistent with the description and spirit of the operation and function disclosed herein. Similarly, the scope of the patent application should be interpreted broadly.

The description of the invention in its many specific examples herein is essentially illustrative, and therefore, variations that do not depart from the spirit and scope of the invention are intended to be within its scope. Such variations should not be considered as departing from the spirit and scope of the invention.

10: Optical Device 20: Substrate 30: Coating 30a: Anti-reflective coating with anti-fouling treatment 30b: Conductive coating 30c: Anti-glare coating 30d: Bandpass filter 30e: Anti-reflective coating 100: Optical Device 110a: First substrate 110b: Second substrate

The disclosure of the present invention can be more fully understood from the embodiments and accompanying drawings in several aspects and specific examples, wherein:

[Figure 1] is a cross-sectional view of an optical device according to the present invention;

[Figure 2] is a cross-sectional view of another type of optical device according to the present invention;

[Figure 3] is a cross-sectional view of another type of optical device according to the present invention;

[Figure 4] is a cross-sectional view of another type of optical device according to the present invention;

[Figure 5] is a cross-sectional view of another type of optical device according to the present invention; and

[Figure 6] is a cross-sectional view of another type of optical device according to the present invention;

Throughout this manual and the diagrams, use the symbols for similar components to identify them.

10: Optical Device 20: Substrate 30: Coating

Claims (16)

An optical device applied to a LIDAR (Light Detection and Ranging) sensor, the optical device comprising: a substrate having a first side facing the environment and a second side facing the LIDAR sensor; a first coating applied to the first side of the substrate, the first coating being selected from an anti-reflective coating, a protective coating, and a conductive coating, wherein the optical device has a first side exposed to the environment and a second side facing the LIDAR sensor, and the conductive coating is present on the second side of the optical device. The optical device of claim 1, wherein the substrate includes plastic, synthetic sapphire, glass and synthetic diamond. The optical device of claim 1, wherein the optical device comprises two or more substrates. The optical device of claim 3, wherein two or more substrates are laminates. The optical device of claim 1, wherein the first coating is an anti-reflective coating. The optical device of claim 1, wherein the first coating is a protective coating. As in claim 6, the optical device wherein the protective coating is applied to an antireflective coating, which is applied to the substrate. The optical device of claim 7, wherein the protective coating and the anti-reflective coating are both on the first side of the optical device. The optical device of claim 7, wherein the protective coating is present on the first side of the optical device. The optical device of claim 1 further includes an anti-glare coating. The optical device of claim 1 further includes a bandpass filter. The optical device of claim 11, wherein the bandpass filter is present on the second side of the optical device. The optical device of claim 11, wherein the bandpass filter is applied to an anti-glare coating, the anti-glare coating is applied to a conductive coating, and the conductive coating is applied to a substrate. The optical device of claim 13, wherein the bandpass filter, the anti-glare coating, and the conductive coating are all located on the second side of the optical device. An optical device applied to a LIDAR (Light Detection and Ranging) sensor, the optical device comprising: a substrate having a first side facing the environment and a second side facing the LIDAR sensor; a first coating applied to the first side of the substrate, the first coating being selected from an anti-reflective coating and a protective coating, and an anti-glare coating, wherein the optical device has a first side exposed to the environment and a second side facing the LIDAR sensor, and wherein the anti-glare coating is applied to the second side of the optical device. The optical device of claim 15, wherein the anti-glare coating and the conductive coating are both on the second side of the optical device.